public int Hash(Vector3 p)
{
for (int i = 0; i < count; i++)
{
var item = buckets[i];
float diffX = p.x - item.x;
float diffY = p.y - item.y;
float diffZ = p.z - item.z;
float sqrMag = diffX * diffX + diffY * diffY + diffZ * diffZ;
if (sqrMag < bucketSize2)
{
return(i);
}
}
if (count >= buckets.Length)
{
Exploder2DUtils.Log("Hash out of range: " + count + " " + buckets.Length);
return(count - 1);
}
buckets[count++] = p;
return(count - 1);
}
/// <summary>
/// Compute intersection between a segment line (a, b) and a plane (p)
/// from Real-Time Collision Detection Book by Christer Ericson
/// </summary>
/// <param name="a">first point of a segment</param>
/// <param name="b">second point of a segment</param>
/// <param name="t">normalized distance of intersection point on vector (ab)</param>
/// <param name="q">point in intersection</param>
/// <returns>true if there is an intersection</returns>
public bool IntersectSegment(Vector2 a, Vector2 b, out float t, ref Vector2 q)
{
var abx = b.x - a.x;
var aby = b.y - a.y;
var dot0 = Normal.x * a.x + Normal.y * a.y;
var dot1 = Normal.x * abx + Normal.y * aby;
t = (Distance - dot0) / dot1;
if (t >= 0.0f - epsylon && t <= 1.0f + epsylon)
{
q.x = a.x + t * abx;
q.y = a.y + t * aby;
return(true);
}
Exploder2DUtils.Log("IntersectSegment failed: " + t);
q = Vector2.zero;
return(false);
}
/// <summary>
/// find and isolate independent (not connecting) parts in a mesh
/// </summary>
public static List <CutterMesh> IsolateMeshIslands(SpriteMesh mesh)
{
var triangles = mesh.triangles;
var vertexCount = mesh.vertices.Length;
// cache mesh data
var trianglesNum = mesh.triangles.Length;
var vertices = mesh.vertices;
if (trianglesNum <= 3)
{
return(null);
}
Exploder2DUtils.Assert(trianglesNum > 3, "IsolateMeshIslands error: " + trianglesNum);
var lsHash = new LSHash(0.1f, vertexCount);
var vertHash = new int[trianglesNum];
for (int i = 0; i < trianglesNum; i++)
{
vertHash[i] = lsHash.Hash(vertices[triangles[i]]);
}
var islands = new List <HashSet <int> > {
new HashSet <int> {
vertHash[0], vertHash[1], vertHash[2]
}
};
var islandsIdx = new List <List <int> > {
new List <int>(trianglesNum)
{
0, 1, 2
}
};
var triVisited = new bool[trianglesNum];
triVisited[0] = true;
triVisited[1] = true;
triVisited[2] = true;
var currIsland = islands[0];
var currIslandIdx = islandsIdx[0];
var counter = 3;
var lastInvalidIdx = -1;
var loopCounter = 0;
while (true)
{
var foundIsland = false;
for (int j = 3; j < trianglesNum; j += 3)
{
if (triVisited[j])
{
continue;
}
if (currIsland.Contains(vertHash[j]) ||
currIsland.Contains(vertHash[j + 1]) ||
currIsland.Contains(vertHash[j + 2]))
{
currIsland.Add(vertHash[j]);
currIsland.Add(vertHash[j + 1]);
currIsland.Add(vertHash[j + 2]);
currIslandIdx.Add(j);
currIslandIdx.Add(j + 1);
currIslandIdx.Add(j + 2);
triVisited[j] = true;
triVisited[j + 1] = true;
triVisited[j + 2] = true;
counter += 3;
foundIsland = true;
}
else
{
lastInvalidIdx = j;
}
}
if (counter == trianglesNum)
{
break;
}
if (!foundIsland)
{
// create new island
currIsland = new HashSet <int> {
vertHash[lastInvalidIdx], vertHash[lastInvalidIdx + 1], vertHash[lastInvalidIdx + 2]
};
currIslandIdx = new List <int>(trianglesNum / 2)
{
lastInvalidIdx, lastInvalidIdx + 1, lastInvalidIdx + 2
};
islands.Add(currIsland);
islandsIdx.Add(currIslandIdx);
}
loopCounter++;
if (loopCounter > 100)
{
Exploder2DUtils.Log("10000 loop exceeded, islands: " + islands.Count);
break;
}
}
var islandNum = islands.Count;
Exploder2DUtils.Assert(islandNum >= 1, "No island found!");
// no more than one islands
if (islandNum == 1)
{
return(null);
}
var result = new List <CutterMesh>(islands.Count);
foreach (var island in islandsIdx)
{
var cutterMesh = new CutterMesh {
mesh = new SpriteMesh()
};
var triCount = island.Count;
var m = cutterMesh.mesh;
var tt = new List <int>(triCount);
var vs = new List <Vector2>(triCount);
var triCache = new Dictionary <int, int>(trianglesNum);
var centroid = Vector2.zero;
var centroidCounter = 0;
var triCounter = 0;
foreach (var i in island)
{
var tri = triangles[i];
var id = 0;
if (triCache.TryGetValue(tri, out id))
{
tt.Add(id);
continue;
}
tt.Add(triCounter);
triCache.Add(tri, triCounter);
triCounter++;
centroid += vertices[tri];
centroidCounter++;
vs.Add(vertices[tri]);
}
m.vertices = vs.ToArray();
m.triangles = tt.ToArray();
cutterMesh.centroidLocal = centroid / centroidCounter;
result.Add(cutterMesh);
}
return(result);
}
/// <summary>
/// cut mesh by plane
/// </summary>
/// <param name="spriteMesh">mesh to cut</param>
/// <param name="meshTransform">transformation of the mesh</param>
/// <param name="line2D">cutting plane</param>
/// <returns>processing time</returns>
public float Cut(SpriteMesh spriteMesh, Transform meshTransform, Math.Line2D line2D, ref List <CutterMesh> meshes)
{
var stopWatch = new Stopwatch();
stopWatch.Start();
#if PROFILING
MeasureIt.Begin("CutAllocations");
#endif
// cache mesh data
var trianglesNum = spriteMesh.triangles.Length;
var verticesNum = spriteMesh.vertices.Length;
var meshTriangles = spriteMesh.triangles;
var meshVertices = spriteMesh.vertices;
// preallocate buffers
AllocateBuffers(trianglesNum, verticesNum);
CutterMesh mesh0, mesh1;
#if PROFILING
MeasureIt.End("CutAllocations");
MeasureIt.Begin("CutCycleFirstPass");
#endif
// inverse transform cutting plane
// line2D.InverseTransform(meshTransform);
// first pass - find complete triangles on both sides of the plane
for (int i = 0; i < trianglesNum; i += 3)
{
// get triangle points
var v0 = meshVertices[meshTriangles[i]];
var v1 = meshVertices[meshTriangles[i + 1]];
var v2 = meshVertices[meshTriangles[i + 2]];
var side0 = line2D.GetSideFix(ref v0);
var side1 = line2D.GetSideFix(ref v1);
var side2 = line2D.GetSideFix(ref v2);
meshVertices[meshTriangles[i]] = v0;
meshVertices[meshTriangles[i + 1]] = v1;
meshVertices[meshTriangles[i + 2]] = v2;
// Utils.Log(plane.Pnt + " " + v0 + " " + v1 + " " + " " + v2);
// all points on one side
if (side0 == side1 && side1 == side2)
{
var idx = side0 ? 0 : 1;
if (meshTriangles[i] >= triCache.Length)
{
Exploder2DUtils.Log("TriCacheError " + meshTriangles[i] + " " + triCache.Length + " " + meshVertices.Length);
}
if (triCache[meshTriangles[i]] == 0)
{
triangles[idx].Add(triCounter[idx]);
vertices[idx].Add(meshVertices[meshTriangles[i]]);
centroid[idx] += meshVertices[meshTriangles[i]];
triCache[meshTriangles[i]] = triCounter[idx] + 1;
triCounter[idx]++;
}
else
{
triangles[idx].Add(triCache[meshTriangles[i]] - 1);
}
if (triCache[meshTriangles[i + 1]] == 0)
{
triangles[idx].Add(triCounter[idx]);
vertices[idx].Add(meshVertices[meshTriangles[i + 1]]);
centroid[idx] += meshVertices[meshTriangles[i + 1]];
triCache[meshTriangles[i + 1]] = triCounter[idx] + 1;
triCounter[idx]++;
}
else
{
triangles[idx].Add(triCache[meshTriangles[i + 1]] - 1);
}
if (triCache[meshTriangles[i + 2]] == 0)
{
triangles[idx].Add(triCounter[idx]);
vertices[idx].Add(meshVertices[meshTriangles[i + 2]]);
centroid[idx] += meshVertices[meshTriangles[i + 2]];
triCache[meshTriangles[i + 2]] = triCounter[idx] + 1;
triCounter[idx]++;
}
else
{
triangles[idx].Add(triCache[meshTriangles[i + 2]] - 1);
}
}
else
{
// intersection triangles add to list and process it in second pass
cutTris.Add(i);
}
}
if (vertices[0].Count == 0)
{
centroid[0] = meshVertices[0];
}
else
{
centroid[0] /= vertices[0].Count;
}
if (vertices[1].Count == 0)
{
centroid[1] = meshVertices[1];
}
else
{
centroid[1] /= vertices[1].Count;
}
#if PROFILING
MeasureIt.End("CutCycleFirstPass");
MeasureIt.Begin("CutCycleSecondPass");
#endif
mesh0.centroidLocal = centroid[0];
mesh1.centroidLocal = centroid[1];
mesh0.mesh = null;
mesh1.mesh = null;
if (cutTris.Count < 1)
{
stopWatch.Stop();
return(stopWatch.ElapsedMilliseconds);
}
AllocateContours(cutTris.Count);
// second pass - cut intersecting triangles in half
foreach (var cutTri in cutTris)
{
var triangle = new Triangle
{
ids = new[] { meshTriangles[cutTri + 0], meshTriangles[cutTri + 1], meshTriangles[cutTri + 2] },
pos = new[] { meshVertices[meshTriangles[cutTri + 0]], meshVertices[meshTriangles[cutTri + 1]], meshVertices[meshTriangles[cutTri + 2]] },
};
// check points with a plane
var side0 = line2D.GetSide(triangle.pos[0]);
var side1 = line2D.GetSide(triangle.pos[1]);
var side2 = line2D.GetSide(triangle.pos[2]);
float t0, t1;
Vector2 s0 = Vector2.zero, s1 = Vector2.zero;
var idxLeft = side0 ? 0 : 1;
var idxRight = 1 - idxLeft;
if (side0 == side1)
{
var a = line2D.IntersectSegment(triangle.pos[2], triangle.pos[0], out t0, ref s0);
var b = line2D.IntersectSegment(triangle.pos[2], triangle.pos[1], out t1, ref s1);
Exploder2DUtils.Assert(a && b, "!!!!!!!!!!!!!!!");
// left side ... 2 triangles
var s0Left = AddIntersectionPoint(s0, triangle.ids[2], triangle.ids[0], cutVertCache[idxLeft], vertices[idxLeft]);
var s1Left = AddIntersectionPoint(s1, triangle.ids[2], triangle.ids[1], cutVertCache[idxLeft], vertices[idxLeft]);
var v0Left = AddTrianglePoint(triangle.pos[0], triangle.ids[0], triCache, cornerVertCache[idxLeft], vertices[idxLeft]);
var v1Left = AddTrianglePoint(triangle.pos[1], triangle.ids[1], triCache, cornerVertCache[idxLeft], vertices[idxLeft]);
// Triangle (s0, v0, s1)
triangles[idxLeft].Add(s0Left);
triangles[idxLeft].Add(v0Left);
triangles[idxLeft].Add(s1Left);
// Triangle (s1, v0, v1)
triangles[idxLeft].Add(s1Left);
triangles[idxLeft].Add(v0Left);
triangles[idxLeft].Add(v1Left);
// right side ... 1 triangle
var s0Right = AddIntersectionPoint(s0, triangle.ids[2], triangle.ids[0], cutVertCache[idxRight], vertices[idxRight]);
var s1Right = AddIntersectionPoint(s1, triangle.ids[2], triangle.ids[1], cutVertCache[idxRight], vertices[idxRight]);
var v2Right = AddTrianglePoint(triangle.pos[2], triangle.ids[2], triCache, cornerVertCache[idxRight], vertices[idxRight]);
// Triangle (v2, s0, s1)
triangles[idxRight].Add(v2Right);
triangles[idxRight].Add(s0Right);
triangles[idxRight].Add(s1Right);
}
else if (side0 == side2)
{
var a = line2D.IntersectSegment(triangle.pos[1], triangle.pos[0], out t0, ref s1);
var b = line2D.IntersectSegment(triangle.pos[1], triangle.pos[2], out t1, ref s0);
Exploder2DUtils.Assert(a && b, "!!!!!!!!!!!!!");
// left side ... 2 triangles
var s0Left = AddIntersectionPoint(s0, triangle.ids[1], triangle.ids[2], cutVertCache[idxLeft], vertices[idxLeft]);
var s1Left = AddIntersectionPoint(s1, triangle.ids[1], triangle.ids[0], cutVertCache[idxLeft], vertices[idxLeft]);
var v0Left = AddTrianglePoint(triangle.pos[0], triangle.ids[0], triCache, cornerVertCache[idxLeft], vertices[idxLeft]);
var v2Left = AddTrianglePoint(triangle.pos[2], triangle.ids[2], triCache, cornerVertCache[idxLeft], vertices[idxLeft]);
// Triangle (v2, s1, s0)
triangles[idxLeft].Add(v2Left);
triangles[idxLeft].Add(s1Left);
triangles[idxLeft].Add(s0Left);
// Triangle (v2, v0, s1)
triangles[idxLeft].Add(v2Left);
triangles[idxLeft].Add(v0Left);
triangles[idxLeft].Add(s1Left);
// right side ... 1 triangle
var s0Right = AddIntersectionPoint(s0, triangle.ids[1], triangle.ids[2], cutVertCache[idxRight], vertices[idxRight]);
var s1Right = AddIntersectionPoint(s1, triangle.ids[1], triangle.ids[0], cutVertCache[idxRight], vertices[idxRight]);
var v1Right = AddTrianglePoint(triangle.pos[1], triangle.ids[1], triCache, cornerVertCache[idxRight], vertices[idxRight]);
// Triangle (s0, s1, v1)
triangles[idxRight].Add(s0Right);
triangles[idxRight].Add(s1Right);
triangles[idxRight].Add(v1Right);
}
else
{
var a = line2D.IntersectSegment(triangle.pos[0], triangle.pos[1], out t0, ref s0);
var b = line2D.IntersectSegment(triangle.pos[0], triangle.pos[2], out t1, ref s1);
Exploder2DUtils.Assert(a && b, "!!!!!!!!!!!!!");
// right side ... 2 triangles
var s0Right = AddIntersectionPoint(s0, triangle.ids[0], triangle.ids[1], cutVertCache[idxRight], vertices[idxRight]);
var s1Right = AddIntersectionPoint(s1, triangle.ids[0], triangle.ids[2], cutVertCache[idxRight], vertices[idxRight]);
var v1Right = AddTrianglePoint(triangle.pos[1], triangle.ids[1], triCache, cornerVertCache[idxRight], vertices[idxRight]);
var v2Right = AddTrianglePoint(triangle.pos[2], triangle.ids[2], triCache, cornerVertCache[idxRight], vertices[idxRight]);
// Triangle (v2, s1, v1)
triangles[idxRight].Add(v2Right);
triangles[idxRight].Add(s1Right);
triangles[idxRight].Add(v1Right);
// Triangle (s1, s0, v1)
triangles[idxRight].Add(s1Right);
triangles[idxRight].Add(s0Right);
triangles[idxRight].Add(v1Right);
// left side ... 1 triangle
var s0Left = AddIntersectionPoint(s0, triangle.ids[0], triangle.ids[1], cutVertCache[idxLeft], vertices[idxLeft]);
var s1Left = AddIntersectionPoint(s1, triangle.ids[0], triangle.ids[2], cutVertCache[idxLeft], vertices[idxLeft]);
var v0Left = AddTrianglePoint(triangle.pos[0], triangle.ids[0], triCache, cornerVertCache[idxLeft], vertices[idxLeft]);
// Triangle (s1, v0, s0)
triangles[idxLeft].Add(s1Left);
triangles[idxLeft].Add(v0Left);
triangles[idxLeft].Add(s0Left);
}
}
#if PROFILING
MeasureIt.End("CutCycleSecondPass");
#endif
List <int>[] trianglesCut = null;
if (vertices[0].Count > 3 && vertices[1].Count > 3)
{
#if PROFILING
MeasureIt.Begin("CutEndCopyBack");
#endif
mesh0.mesh = new SpriteMesh();
mesh1.mesh = new SpriteMesh();
var verticesArray0 = vertices[0].ToArray();
var verticesArray1 = vertices[1].ToArray();
mesh0.mesh.vertices = verticesArray0;
mesh1.mesh.vertices = verticesArray1;
if (trianglesCut != null && trianglesCut[0].Count > 3)
{
triangles[0].AddRange(trianglesCut[0]);
triangles[1].AddRange(trianglesCut[1]);
}
mesh0.mesh.triangles = triangles[0].ToArray();
mesh1.mesh.triangles = triangles[1].ToArray();
mesh0.centroidLocal = Vector2.zero;
mesh1.centroidLocal = Vector2.zero;
foreach (var p in vertices[0])
{
mesh0.centroidLocal += p;
}
mesh0.centroidLocal /= vertices[0].Count;
foreach (var p in vertices[1])
{
mesh1.centroidLocal += p;
}
mesh1.centroidLocal /= vertices[1].Count;
#if PROFILING
MeasureIt.End("CutEndCopyBack");
#endif
meshes = new List <CutterMesh> {
mesh0, mesh1
};
stopWatch.Stop();
return(stopWatch.ElapsedMilliseconds);
}
stopWatch.Stop();
// UnityEngine.Debug.Log("Empty cut! " + vertices[0].Count + " " + vertices[1].Count);
return(stopWatch.ElapsedMilliseconds);
}